Stationary contact having sealing gasket support structure



July 21, 1970 I J. R. MCCLOUD 3,521,016

l STATIONARY CONTACT HAVING SEALING GASKET SUPPORT STRUCTURE Filed Dec. 29, 196e 4 sheets-sheet 1 July 21, 1970 J. R. MCCLO'UD v 3,521,016

STATIONARY CONTACT HAVING SEALING GASKET SUPPORT STRUCTURE Filed Dc. 29, 196e 4 sheets-sheet ,g

July 21, 1970v J. R. MccLoUD 3,521,016

STATIONARY CONTACT HAVING SEALING GASKET SUPPORT STRUCTURE' Filed Deo. 29, 1966 l i 4 Sheets-Sheet I5 ,y Il' l` E I lwoma l I 1v a i 'July 21 1970 J. R.. MccLouD 3,521,016

sTA'rIoNAaY CONTACT HAVING sEALING GASKET SUPPORT STRUCTURE Filed Dec. 29, 196e y 4 4 sheets-sheet 4 JAA/ffy f? /Wzda United States Patent O M 3,521,016 STATEONARY CONTACT HAVING SEALING GASKET SUPPORT STRUCTURE James R. McCloud, Burbank, Calif., assignor, by mesne assignments, to I-T-E Imperial Corporation, Philadelphia, Pa., a corporation of Delaware Filed Dec. 29, 1966, Ser. No. 605,795 Int. Cl. H01h 33/83 U.S. Cl. 200-148 3 Claims ABSTRACT OF THE DISCLOSURE The stationary contact of a gas blast circuit breaker contains a discharge orice having a blast valve seal ring therein. The blast valve seal ring is held in position by an insulation clamp which has an interior surface which is continuous with the interior surface of the conductive material of the stationary contact, with the seal ring extending above this interior surface.

The above noted application describes a novel gas blast circuit interrupter structure in which a blast valve is slidably mounted on the movable contact and forms a seal around the movable contact to an annular gasket ernbedded in the stationary contact. By placing the blast valve in immediate proximity to the regio-n between the separating contacts, the structure of the above noted application obtains improved operating characteristics since the air blast is immediately applied to any arc drawn between the cooperating contacts when the contacts open.

It has been found that the high pressure applied to the annular gasket tends to force the gasket out of its position on the stationary contact; and further that the stationary contact region above the gasket is subject to burning or erosion.

ln accordance with the present invention, the stationary contact is constructed such that an insulation clamp is located in the stationary Contact surface above the annular gasket to securely clamp the gasket in position and to offer a non-carbonizing surface in the region where considerable contact erosion and burning previously occurred.

Accordingly, a primary object of this invention is to provide a novel stationary Contact structure for gas blast circuit breakers which eliminates` contact erosion by placing a non-carbonizing surface in the region formerly subjected to erosion.

Another object of this inVentio-n is to provide a novel insulation clamp for securing the annular gasket of a blast valve in position while further providing a noncarbonizing surface portion on a stationary contact.

3,521,016 Patented July 2l, 1970 These and ot er objects of this invention will become apparent from the following description when taken in connection with the drawings, in which:

FIG. 1 is a cross-sectional view of the novel interrupter structure of the invention in the open position.

FIG. 2 is similar to FIG. 1 and shows the interrupter structure in its closed position.

FIG. 3 is a. bottom plan view of the stationary contact of FIG. 1.

FIG. 4 is a cross-sectional View of the upper terminal structure for the interrupter for FIGS. 1 and 2.

FIG. 5 is a cross-sectional view of FIG. l taken across lines 5 5 in FIG. l.

FIG. 6 shows a modified stationary contact structure of the type generally shown in FIGS. 1 and 2 which incorporates a novel insulation member in the stationary contact surface which clamps the annular air blast valve gasket in position in accordance with the present invention.

Referring now to the drawings, the interrupter chamber is comprised of an insulation tube 10 of suitable material which is fitted and sealed in conductive mounting disks 11 and 12 at its upper and lower ends, respectively. Upper disk 11 is then secured to the disk-shaped stationary contact 12a, shown in bottom plan view in FIG. 3. A gas conducting discharge outlet including tube 13 shown in FIG. 4 is connected atop Contact 12a and contains a standard stationary arcing contact linger 14 surrounded by a cooler honeycomb 15, schematically illustrated, which conducts blast gas through openings in terminal plate 16 to the exterior of the interrupter. The bottom disk 12 is then secured to bottom castings 20.

Bottom casting 20 is secured and sealed on the end of a suitable hollow support insulator 21 with a source of high pressure gas, such as air (not shown) connected to the bottom of insulator 21 and thus to central chamber 22 beneath casting 20. Casting 20 has a channel 23 for conducting this high pressure gas through valve seat 24 formed in casting 20. A valve member 25 carried on rod 26 is then movable between valve seat 24 and valve seat 27 which is suitably fastened to bottom casting 20, with valve member 25 normally biased toward engagement with valve seat 27 by the compression spring 28. A suitable operating mechanism (not shown) is connected to rod 26 from some remote position and is responsible for movement of valve 25 as will be later described.

Channel 23 then communicates with channel 28a in bottom casting 20. The upper portion of channel 28a leads into an annular channnel 28a surrounding lower conductive member 29 which is secured to casting 20. Conductive member 29 has a flange 30 thereon and concentrically surrounds a cooler honeycomb 31 through which arc products and gases may pass to the outlet channel 31a in bottom casting 20 to the external atmosphere.

A movable contact rod 32 having an upper contact sec tion 33 and a lower tail section 34 is then provided with the lower section 34 in sliding relation within member 29 as illustrated. The movable contact rod 32 has an opening 35 extending therethrough, and is provided with a series of resilient buffer plates such as plates 36, 37 and 38, the bottom plate of rwhich is received by the top of member 29 when the movable Contact 32 is in the open position shown in FIG. 1.

A biasing spring 39 contained between ilange 30 of xed member 29 and flange 40 of the movable contact rod 32 then biases the contact rod 32 upwardly toward the position of FIG. 2.

Contact rod 32 is in sliding contact engagement with upper conductive cylinder portion 50 of bottom casting 20 by means of a plurality of sliding contacts 51 which surround the contact rod 32. By way of example, six such sliding contacts 51 can surround rod 32 as illustrated in FIG. 5. Each of contacts 51 are then biased outwardly and into sliding engagement with member 50 as by suitable compression springs 52.

The exterior surface of contact rod 32 is then provided with a shoulder 60 which serves as a stop for annular blast valve member 61 which telescopes over the upper end of contact rod 32. A spring 61a is provided between shoulder 61b on movable contact rod 32 and the interior of valve `61 Which biases valve 61 upwardly with respect to contact rod 32. Blast valve member 61 has a lower cylindrical skirt 62 which lits over member S0 with a gas-tight seal formed between members 61 and 50 by the O-ring 67. A second seal is formed between member 61 and contact rod 32 by the O-ring 68.

Annular valve 61 is then movable from the lower open position of FIG. l to the valve closed position of FIG. 2 where the outer surface annular valve 61 seats against O-ring -69 carried in the stationary contact 12a.

It is to be noted that movable contact rod 32 is movable independently of valve y61 to the disengaged position (from the position of FIG. 2 to the position of FIG. 1), and that when the contact 32 engages stationary contact 12a, it engages on a radially inwardly directed portion 70 of the inverted S-shaped engaging surface of stationary contact 12a.

An annular cavity 80 is then provided within skirt -62 -which is connected to channel 28a to permit compressed gas from cavity 22 to fill cavity 80. Channel 22 is connected to main annular chamber 81 formed between the interior of tube and the exterior of extension 50 by virtue of the spider type construction of casting 20 as illustrated by dotted lines in FIGS. 1 and 2. Note that channel 28a and chamber 81 are in communication with one another only when valve 25 is in the position shown in FIGS. 1 and 2, through the common channels 23 and 28. When valve 25 moves down (and seats on valve seat 24) channel 28a and chamber 81 are isolated by valve 2S.

The operation of the interrupter of FIGS. 1 and 2 is as follows:

With the circuit interrupter in the closed position of FIG. 2, compressed air is admitted through chamber 22 through conduits 23 and 28, the valve 25 being in its upper position where it seats against valve seat 27. The pressure from chamber 28 is then applied under flange 40 of movable contact 52 to aid spring 39 in closing contact rod 32, and to the interior volume 80 under valve 61 to aid spring 61a to close the valve 61, thereby to bias both valve y61 and contact 32 to the engaged position in FIG. 2. The valve `61 seats on ring 69, thereby to prevent compressed air in chamber 81 from escaping through the center of contact 12a or through channel 35 in contact rod 32.

In order to open the circuit interrupter, the valve 25 is remotely actuated through a suitable operating mechanism which is unimportant for purposes of the present invention, whereby the valve 25 is moved down to seat against valve seat 24. This then vents chamber 28a to the external atmosphere, thereby permitting the pressure beneath the annular valve 61 to fall off rapidly. The valve 61 is so proportioned that the area under the valve within chamber 80is less than the area at the top of the valve exposed to the pressure within the outer chamber 81, thereby tending to move the valve toward its lower or open position against the force of spring 61a. Moreover, when the pressure has fallen suiciently to allow the valve to move downwardly and break the seal at gasket 69, the area on top of the valve subject to the higher chamber pressure will now be equivalent to the full area of the valve including the area which was internal of seal 69 which was exposed only to external pressure. This sudden increase in area and resultant multiplication of opening force Will then drive valve 61 rapidly down against shoulder 60 of movable contact 32 and independently of movement of movable contact l62.

When the valve 25 vents chamber 28a, pressure under ange 40 of movable contact rod 32 was also removed. However, the force of spring 39 is still sufficient to hold contact rod 32 in engagement with stationary Contact 12a. As soon as valve 61 leaves seal `69, however, the entire upper surface of contact 32 is exposed to the high pressure of chamber 81 which is suicient to move contact rod 32 rapidly downward against the force of spring 39.That is, in FIG. 2, the surface of valve 61 is divided into an interior annular region 61Cv and an exterior annular region 61d, by engagement of gasket 69 and vvalve 61. When the valve opens, both areas 61C and 61d are exposed to high pressure.

Consequently, in operation, valve 61 is initially unsealed from seal 69 whereupon it immediately moves downward, independently of contact 32, with a popping type action once the remainder of its internal area within seal 69 is exposed. Similarly, the movable contact is exposed to high operating pressure immediately after valve 69 is opened whereupon contact 32 also moves down with a popping action. Since valve 61 opens immediatelyprior to separation of contacts 32 and 12a, a strong air blast will be established between the separating contacts to extinguish any arc drawn therebetween. This air blast is then conducted through the cooler honeycomb `15 (FIG. 4) 4to external atmosphere, and through central opening 35 and through honeycomb 31 to external atmosphere. Note fur-l ther that there is no delay in application of blast air to the Contact after the blast valve is opened since this air (and the blast valve) surrounds the contact area and need not be conducted through auxiliary channels. Thus, air blast need continue only long enough to extinguish the arc whereby compressed air of the supply is conserved. Moreover, the air pressure at the contacts has the same pressure as the supply source (as measured in cavity '22), and it is not necessary to increase the air supply pressure to account for pressure drops in conduits leading from the blast valve to the contact.

In order to shut ofrr the blast of air and reset the contacts, the operating mechanism moving valve 25 is suitably arranged so that the valve 25 is automatically returned to the position shown in the drawings where the valve 25 seats against valve seat 27. This action will permit compressed air to enter channel 28a. and chamber 80, thereby moving the valve 61 upwardly to seal against O-ring 69 with a snap action. The closing of valve 61 removes the pressure from the top of contact 32 whereby the pressure beneath flange 40 and spring 39 will move contact 32 toward its engaged position with a subsequent snap action.

Note that a supplemental isolating contact means (not shown) will be connected in series with the interrupter contacts in the usual manner. This interrupter ris synchronized with the operation of valve25 to establish an open circuit to prevent the reclosing of contact 3-2 from reestablishing the circuit which has been opened.

It is to be particularly noted that the air pressure within the movable contact chamber acts independently on both contact 32 and annular valve 61. In this manner, the contact force is made independent of the sealing force and adds to the force obtained from the main closing spring 39. This results in high contact pressure between contacts 32 and 12a up to the instant of contact separation. At the same time, the force under annular valve 61 is proportionally lower so as to not develop excessive sealing pressure, thereby allowing the valve to be of light construction so that it will be rapidly movable under the differential pressures applied thereto during opening.

Referring now to FIG. 6, there is illustrated therein a modification of the stationary contact structure shown in FIGS. 1 and 2 which incorporates the present invention and illustrates other construction variations.

FIG. 6 illustrates the upper conductive mounting disk 11 which receives the main insulation tube 10 and is secured to its top. A modied stationary contact 100 is provided with an outer shoulder 101 which can, for example, receive a suitable discharge outlet including tube 13 of FIGS. 1 and 2.

FIG. 6 additionally shows the upper portion of sleeve 50 which contains movable contact 32. Note that in FIG. 6 the movable contact 32 is composed of three sections: A lower body section 32a which threadedly receives the upper contact section 32b which is terminated with an arcing tip 32e` which could be composed of some suitable arc resistant material. In addition, the movable valve 61 is shown with a foreshortened nose section 61b which terminates on gasket 67 in the manner disclosed in copending application, Ser. No. 611,600, led Jan. 25, 1967 entitled Shaped Nose Section on Movable Ring Valve, in the name of Daniel H. McKeough.

The stationary contact 100 is then composed of a plurality of sections including lower ring 110 which is sealed to external tube by a suitable gasket 111. Note further that a conductive liner 112, which may be of aluminum, is suitably bolted around the upper interior of tube 10 to prevent burning of the interior of glass tube 10 if ionized air should be blown back into chamber 81.

The annular gasket 69 which cooperates with valve 61 is then clamped into position within shoulder 113 of ring 110 by an insulation clamp 114. The insulation clamp 114 is formed of a suitable non-carbonizing insulation material such as Teiion and its outer surface is presented to and is continuous with the outer surface of arcing contact section 32C of the movable contact 32. An arcing contact ring 120 is then placed on top of insulation ring 114 and is composed of a conductive body 121 having an internal lining of suitable arc resistant material which forms the contacting portion of the stationary contact which cooperates with arcing tip 32C of movable contact 32.

The entire stationary contact assembly is then held in position by means of the upper conductive clamping plate 123 which is held in position by suitable bolts such as bolt 124 which extends through clamping plate 123 and plate 120 and is threaded into tapped openings in ring 110.

It is to be noted that an insulation spacer 125 is disposed between interior portions of clamp 123 and Contact section 120 in order to define the current path 126, shown in Vdotted lines from stationary Contact 100 to the movable contact 32 and will create a blow out force tending to drive the arc drawn between arcing contact sections 32C and 122 outwardly rather than toward the interior of chamber 81. This arrangement is the subject of copending application, Ser. No. 612,216, tiled Jan. 27, 1967 entitled Stationary Contact Structure Forcing Blow Out Shaped Current Path, in the name of Lorne D. McConnell, and assigned to the assignee of the present invention.

The present invention is directed to the novel manner in which gasket 69 is rigidly held in position by the insulation spacer 116 to prevent the accidental release of the gasket `69 from the stationary Contact structure. Thus, it will be apparent that the spacer structure 114 securely clamps ring 69. Further to this, however, it has been found that in arrangements of the type shown in FIGS. 1 and 2, the contact surface region above gasket 69 was subject to heavy erosion. The use of a non-carbonizing surface in the region illustrated in FIG. `6- for spacer 114 has eliminated this unessential conductive contact surface since no contact is ever made directly to this surface and thus eliminates a source of metal erosion which leads the presence of ionized metallic particles in the ionized products created during arcing.

Moreover, it has been found that high pressure gas upper surface of spacer 114 and the lower contiguous surface of member 121 finally extending to the exterior atmosphere. However, this high pressure gas seepage creates a further downward force on spacer114 tending to hold gasket 69 even more rigidly in position.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A gas blast circuit breaker comprising in combination: a stationary contact; an elongated movable contact movable between an engaged and disengaged position with respect to said stationary contact; an annular blast valve of insulation material surrounding said elongated movable contact; said annular blast valve having an interior surface portion extending along a major portion of the axis thereof; said interior surface portion engaging and being axially slidably movable on the exterior surface of said movable contact; said annular blast valve having first and second opposite annular surfaces facing respectively toward and away from said stationary Contact; a rst chamber in communication with said second annular surface of said blast valve; a high pressure gas source; valve means for selectively connecting said iirst chamber to said high pressure source or to a low pressure exhaust region respectively; a second chamber connected to said high pressure gas source; said movable contact and said annular blast valve contained within said second chamber; an opening in said second chamber adjacent the end of said elongated movable contact and in the region where said movable contact engages said stationary contact; seal ring means disposed in said opening and engageable by an exterior annular region on said iirst annular surface of said annular blast valve; said annular region dividing said iirst annular surface into an interior annular portion and an exterior annular portion; said opening in said second chamber communicating with a low pressure region; said end of said movable contact exposed to said low pressure region when said first annular surface of said annular blast valve engages said seal ring means and said movable contact engages said stationary contact; connection of said iirst chamber to said low pressure region by said valve means permitting the release of said first annular surface of said annular blast valve from said seal ring means whereby high pressure from said second chamber is connected over the full surface area of said iirst annular surface of said blast valve to move said blast valve down along said movable contact and said high pressure source is connected over the end surface of said movable contact, thereby to move said movable contact down and away from said stationary contact with the opening of said blast valve permitting a blast of high pressure gas through the region between the separating movable and stationary contacts; the improvement which comprises an insulation ring for clamping said seal ring means to the surface of said stationary contact; said stationary contact comprising a ring shaped conductive body having a central opening therein defining said opening in said second chamber; said movable contact engaging the interior walls of said central opening at a generally axially central plane around said interior surface; said seal ring means positioned in the surface of said central opening below said generally central plane; said insulation ring secured to the interior surface of said central opening between said generally central plane and the plane of said seal ring means and clamping said seal ring means in engagement with said stationary Contact.

2. The device as set forth in claim 1 wherein the interior surface of said insulation ring is generally continuous with the interior conductive surface of said interior opening.

3. The device as set forth in claim 2 wherein said central opening has a generally conical shape with the apex of said conical shape above said stationary contact.

References Cited UNITED STATES PATENTS 3,226,513 12/ 1965 Frowein et al. 20G- 148 3,236,983 2/1966 Frowein 20G-148 FOREIGN PATENTS Austria. France. Germany. Germany. Switzerland. Germany.

ROBERT K. SCHAEFER, Primary Examiner 10 R. A. VANDERHYE, Assistant Examiner 

